Saturday: 6 July 2013

It's The Month of June, Number 89 in a series. For us in northeast Georgia, it continued cooler than an average June, and our surplus of rain became even larger. It's a little disconcerting how this is so at variance with what's going on outside our region.

Some anomalous warming has continued in the East, but it's a weak signal. The region of unusual warmth in the West continues to expand and deepen, especially in the southwest. The anomalous warmth in NE Georgia is technically accurate, but for unusual reasons seemed cooler. I'll go into those below.

We find the National Weather Service Climate Prediction Center's precipitation plots here.

The plot on the right shows the oddities in the rainfall patterns in June. The pale pastel greens and browns of May have intensified without much movement into much deeper greens or browns. Very dry conditions have spread northward and westward in the Southwest US. The Pacific Northwest, including northern California, are an odd blend of drier *and* wetter than normal.

Much of the east has had or continued to have a surplus of rain.

For the Athens, GA area:

Below is what I've finally come up with as a daily rain/temperature plot. The spiky lines are temperatures recorded during the days, and the lighter blue bars are Wolfskin rainfall measurements.

To my eyes there are two features that stand out. The temperatures were amazingly even throughout the month. We only went above 90 degF three times, which is a very low frequency. The frequent and in many cases high daily rainfall deliveries are also unusual, and we'll get to the below. (We weren't here for the two heaviest rainfalls, which I more or less split evenly, not having an automated rainfall gauge. That's why you don't see any temperature readings, either.)

The average monthly temperature for June was 76.9 degF, just about the same as the 30-year average of 76.8F. This is reflected in the first figure in this post. However our average high was lower than usual, and our average low was higher than usual. This resulted in the evenness of the rain/temperature plot above, and in a general feeling that the month was cooler (cooler days, which people notice, even if the nights were warmer).

So it should come as no surprise that we had, again, 0 day more than 1 standard deviation above normal highs (4.6 normal). We had 2 nights with temperatures more than 1 standard deviation below normal lows (4.9 normal).

The monthly histogram below shows the breakdown of high and low temperature range counts from June 1948 on. The error bars are just plus/minus one standard deviation, which I arbitrarily set as the limits outside of which are "significantly" anomalous.

This time around we do have excursions into significance, if you accept the 1 standard deviation bars as the threshhold. As already mentioned, we had fewer 90-deg days than normal, and they ended up as significant additions of 80s days, 24 such, and significantly higher than the usual 16.

The right side of the figure above shows the same thing: more nights in the 60s, and fewer in the 70s. All this might seem at variance with the overall averages, but that's why a breakdown like this is good.

The figure below shows the Athens precipitation data which are official for our area. As usual the green line shows our actual rainfall, the red shows the average accumulation expected. The black dots are rainfall over the last 22 years, and the river of peach shows the standard deviation.

For the second month in a row, we had the welcome blue of surplus rain, greater than one standard deviation, for most of the month. This time, however, we maintained that surplus through the end of the month. I guess I should really call it a supersurplus.

Here are the remarkable stats:

Our total rainfall out here was 7.20", and the official recording in Athens (shown here) was 8.21". 4.18" is normal for June (yes, the new 30-year average for June is much lower than in past 30-year windows). This was our 7th rainiest June here since 1920, but it isn't that hugely uncommon. Kind of a once in 14-year event.

Overall, we have stayed above average rainfall all year since mid-February. By Wolfskin measurements we are almost at 34" for the year. The usual rainfall by this time is around 25".

Prognosticator stuff:

What is the neat prognosticator telling us? Once again it has told us the truth about the previous month. The West did continue to get hotter and drier than normal, and the East largely was wetter, if not all that much cooler.

As of June 30, the next month has two July predictions of interest: higher rain than normal to the southwest, especially the most afflicted drought regions. This continues for the southeast (except FL), mid Atlantic, and Appalachian states too. Temperatures are predicted to be normal in most regions except for the west, where they are much higher in the Rocky Mountain states. Some improvement for the southwest, except southern California and much of Arizona.

Temperatures seem not unusual over the three month period (JAS)except for the West, where higher than normal is maintained and spreads east into the Plains states, and Texas.

Precipitation continues to be below normal for the Pacific Northwest and west Texas. It continues to be above normal for all the southeast, including Florida. This seems to be a change from merely normal rainfall made a month ago.

ENSO stuff:

The folks at CPC have a version of PDF or HTML that is much different from their previous presentations, but at least it's there and the link isn't broken.

As of Jul 1, ENSO neutral conditions continue, and are expected to remain neutral throughout the Northern Hemisphere summer. We've remained ENSO neutral now for over a year. The last such lengthy period was 10 years ago, 2003-2004. You can't use an El Niño or La Niña to explain extreme weather this year.

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